Standardized Geomorphic Classification of Seafloor Within the United States Atlantic Canyons and Continental Margin Frontiers in Marine Science

Accurate seafloor maps serve as a critical component for understanding marine ecosystems and guiding informed ocean management decisions. From 2004 to 2015, the Atlantic Ocean continental margin offshore of the United States has been systematically mapped using multibeam sonars. This work was done in support of the U.S. Extended Continental Shelf (ECS) Project and for baseline characterization of the Atlantic canyons, but the question remains as to the relevance of these margin-wide data sets for conservation and management decisions pertaining to these areas. This study utilized an automatic segmentation approach to initially identify landform features from the bathymetry of the region, then translated these results into complete coverage geomorphology maps of the region utilizing the coastal and marine ecological classification standard (CMECS) to define geoforms. Abyssal flats make up more than half of the area (53%), with the continental slope flat class making up another 30% of the total area. Flats of any geoform class (including continental shelf flats and guyot flats) make up 83.06% of the study area. Slopes of any geoform class make up a cumulative total of 13.26% of the study region (8.27% abyssal slopes, 3.73% continental slopes, and 1.25% seamount slopes). While ridge features comprise only 1.82% of the total study area (1.03% abyssal ridges, 0.63 continental slope ridge, and 0.16% seamount ridges). Key benefits of the study’s semi-automated approach include computational efficiency for large datasets, and the ability to apply the same methods to large regions with consistent results.

精准的海底地图是认知海洋生态系统、支撑科学合理海洋管理决策的核心要素。2004年至2015年间，科研人员利用多波束声呐（multibeam sonars）对美国近海大西洋大陆边缘开展了系统性海底测绘工作。本次测绘工作旨在支撑美国外大陆架（Extended Continental Shelf, ECS）项目，并完成大西洋峡谷的基础特征表征，但此类覆盖全大陆边缘的数据集在对应区域的保护与管理决策中是否具备应用价值，仍有待进一步验证。本研究采用自动分割方法，首先从该区域的测深数据（bathymetry）中提取地貌特征，随后依据海岸与海洋生态分类标准（Coastal and Marine Ecological Classification Standard, CMECS）定义地貌单元（geoforms），将提取结果整合成覆盖全区域的地貌地图。深海平原占研究区总面积的一半以上（53%），大陆坡平地占比达30%。各类地貌单元的平地（包括大陆架平地、海山平顶平地）合计占研究区总面积的83.06%。各类地貌单元的坡地累计占研究区总面积的13.26%，其中深海坡占8.27%、大陆坡占3.73%、海山坡占1.25%。而脊状地貌仅占研究区总面积的1.82%，具体包括深海脊（1.03%）、大陆坡脊（0.63%）与海山脊（0.16%）。本研究采用的半自动化方法核心优势在于：可高效处理大规模数据集，且能在大区域推广应用并获得一致的分析结果。